Leakage reactance transformer



Dec. 20, 1949 w. KENDRICK 2,491,567

LEAKAGE REACTANCE TRANSFORMER Filed Feb. 24, 1947 Frkjl I 19 20? 1, William Mull-lick.

Patented Dec. 20, 1949 UNITED STATES PATENT OFFICE 2,491,567 LEAKAGE REACTANCE TRANSFORMER William Kendrick, Orange, Calif.

Application February 24, 1947, Serial No. 730,483

1 Claim. 1

The present invention relates to transformers of the high leakage reactance type, and more particularly to such transformers which are suitable for use with gaseous discharge tubes such as neon tubes used for advertising displays.

An object of the invention is to provide, in a device of unitary character, the structural characteristics required to deliver a relatively high alternating current voltage combined with varying current control characteristics, while maintaining a constant magnitude of voltage.

A further object of the invention is to provide a transformer of high leakage reactance sufficient to provide a secondary current of limited maximum magnitude which incorporates in its primary winding facilities, suitable arrangements for adjusting the secondary current. The secondary current is adjustable throughout a range of magnitudes suflicient to produce the desired range of brilliancy in the connected lighting load which may be a neon tube sign, for example.

Another object of the invention is to provide a transformer of the above characteristics which in itself contains no moving parts and which is accordingly capable of being enclosed in a suitable casing and having the casing filled with an insulating compound for protection against moisture and electrolytic corrosion of the fine wire in the secondary windings.

Other and further objects will become apparent upon reading the following specification together with the accompanying drawing forming a part hereof. Referring to the drawing:

Fig. 1 shows a diagrammatic representation of front elevation view of an embodiment of the invention.

Fig. 2 shows an end elevation of the embodiment of Fig. 1.

Fig. 3 shows a simplified circuit diagram of the embodiment illustrated in Figs. 1 and 2, with part of winding l4 omitted for clarity in tracing the circuits.

Referring to Fig. 1, a pair of secondary coils 5s and ii are disposed in spaced relationship on a laminated electromagnetic core l2 which may be of silicon steel, for example. Likewise disposed on core I2 is a primary winding I3 which is situated intermediate the secondary windings ii and l l and which is serially connected to another primary winding !4 by conductor l5, primary windin it being disposed on the opposite leg of core 52 from that on which windings II), II and it are located.

The two high voltage secondary windings l0 and ll are serially interconnected in additive re- 2 lationship by conductor l5. High voltage conductors l6 and l! are shown connected to energize a neon display sign [8.

Primary winding 13 is connected in additive relationship to primary winding 14. Primary winding is is provided with a plurality of tap leads designated generally as 20 and which for simplicity of illustration have been shown as being only four in number. A greater or lesser number of such leads may be provided and the current difference between adjacent leads may be selected to give the desired range of current control and the desired fineness of adjustment.

Correspondingly, a group of tap leads is provided for primary winding l4 and designated generally at I9. These tap leads l9 and 20 terminate at the tap switches 2| and 22 or relays which are connected to the constant potential alternating current supply mains designated A. C. For convenience, in order to obtain the maximum range of control with the minimum number of switch points, the tap leads 20 may be arranged for line adjustment and the tap leads I9 may be arranged for coarse adjustment, the overall current diiference between the extreme tap leads of the fine adjustment group being approximately equal to the voltage difference between adjacent tap leads of the coarse adjustment group.

The leakage reactance required to limit the maximum secondary current is provided by laminated magnetic shunt members 23 and 24. shunts of this type are well known in the transformer art and their operation and arrangement will therefore not be described in detail.

In operation, the desired degree of brilliance for the neon tube display I8 is obtained by selecting the combination of positions of tap switches 2| and 22 or relays which produces the effect sought to be obtained. Since the magnetic shunts 23 and 24 are in fixed positions, they remain effective regardless of the flux density in core l2 until a point is reached where saturation effects become noticeable. In the event that some condition such as a short circuit in the high voltage wiring should tend to draw heavy secondary current, the resulting opposing magnetomotive force produced in the secondary coils tends to force an increased amount of flux produced by the primary windings through the shunt members 23 and 24, thus limiting the maximum secondary current.

While I have shown what I believe to be the best embodiment of my invention, I do not wish to be confined to the embodiment shown but 3 by the scope of the invention as set forth in the appended claim.

I claim:

A transformer of the character described comprising an open electro-magnetic core having spaced legs and yokes connecting the legs together at the ends thereof, a pair of spaced secondary windings on one leg of the core serially connected in additive relationship, a primary winding upon the said leg of the core intermediate the secondary windings, a further primary winding upon the other leg of the core, said primary windings being electrically connected in series relation, a pliuality of tap leads connected to electrically spaced points within and adjacent to one end of the first mentioned primary Winding, a plurality of tap leads connected to electrically spaced points within the further primary winding and adjacent to one end thereof, selectively operable switching means operatively associated with the tap leads of each primary wind- 4 ing, and means for connecting a source of alternating electric current with the remote ends of the serially connected primary windings through the said tap leads.

WILLIAM KENDRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

